From c48802abf2f0912ce3c34775587f674b037939ac Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 10 Oct 2018 20:21:56 +0100 Subject: [PATCH 30/49] blockjob: Wake up BDS when job becomes idle RH-Author: Kevin Wolf Message-id: <20181010202213.7372-18-kwolf@redhat.com> Patchwork-id: 82610 O-Subject: [RHEL-8 qemu-kvm PATCH 27/44] blockjob: Wake up BDS when job becomes idle Bugzilla: 1637976 RH-Acked-by: Max Reitz RH-Acked-by: John Snow RH-Acked-by: Thomas Huth In the context of draining a BDS, the .drained_poll callback of block jobs is called. If this returns true (i.e. there is still some activity pending), the drain operation may call aio_poll() with blocking=true to wait for completion. As soon as the pending activity is completed and the job finally arrives in a quiescent state (i.e. its coroutine either yields with busy=false or terminates), the block job must notify the aio_poll() loop to wake up, otherwise we get a deadlock if both are running in different threads. Signed-off-by: Kevin Wolf Reviewed-by: Fam Zheng Reviewed-by: Max Reitz (cherry picked from commit 34dc97b9a0e592bc466bdb0bbfe45d77304a72b6) Signed-off-by: Kevin Wolf Signed-off-by: Danilo C. L. de Paula --- blockjob.c | 18 ++++++++++++++++++ include/block/blockjob.h | 13 +++++++++++++ include/qemu/job.h | 3 +++ job.c | 7 +++++++ 4 files changed, 41 insertions(+) diff --git a/blockjob.c b/blockjob.c index be5903a..8d27e8e 100644 --- a/blockjob.c +++ b/blockjob.c @@ -221,6 +221,22 @@ int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs, return 0; } +void block_job_wakeup_all_bdrv(BlockJob *job) +{ + GSList *l; + + for (l = job->nodes; l; l = l->next) { + BdrvChild *c = l->data; + bdrv_wakeup(c->bs); + } +} + +static void block_job_on_idle(Notifier *n, void *opaque) +{ + BlockJob *job = opaque; + block_job_wakeup_all_bdrv(job); +} + bool block_job_is_internal(BlockJob *job) { return (job->job.id == NULL); @@ -419,6 +435,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver, job->finalize_completed_notifier.notify = block_job_event_completed; job->pending_notifier.notify = block_job_event_pending; job->ready_notifier.notify = block_job_event_ready; + job->idle_notifier.notify = block_job_on_idle; notifier_list_add(&job->job.on_finalize_cancelled, &job->finalize_cancelled_notifier); @@ -426,6 +443,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver, &job->finalize_completed_notifier); notifier_list_add(&job->job.on_pending, &job->pending_notifier); notifier_list_add(&job->job.on_ready, &job->ready_notifier); + notifier_list_add(&job->job.on_idle, &job->idle_notifier); error_setg(&job->blocker, "block device is in use by block job: %s", job_type_str(&job->job)); diff --git a/include/block/blockjob.h b/include/block/blockjob.h index 32c00b7..2290bbb 100644 --- a/include/block/blockjob.h +++ b/include/block/blockjob.h @@ -70,6 +70,9 @@ typedef struct BlockJob { /** Called when the job transitions to READY */ Notifier ready_notifier; + /** Called when the job coroutine yields or terminates */ + Notifier idle_notifier; + /** BlockDriverStates that are involved in this block job */ GSList *nodes; } BlockJob; @@ -119,6 +122,16 @@ int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs, void block_job_remove_all_bdrv(BlockJob *job); /** + * block_job_wakeup_all_bdrv: + * @job: The block job + * + * Calls bdrv_wakeup() for all BlockDriverStates that have been added to the + * job. This function is to be called whenever child_job_drained_poll() would + * go from true to false to notify waiting drain requests. + */ +void block_job_wakeup_all_bdrv(BlockJob *job); + +/** * block_job_set_speed: * @job: The job to set the speed for. * @speed: The new value diff --git a/include/qemu/job.h b/include/qemu/job.h index fdaa06f..407d549 100644 --- a/include/qemu/job.h +++ b/include/qemu/job.h @@ -156,6 +156,9 @@ typedef struct Job { /** Notifiers called when the job transitions to READY */ NotifierList on_ready; + /** Notifiers called when the job coroutine yields or terminates */ + NotifierList on_idle; + /** Element of the list of jobs */ QLIST_ENTRY(Job) job_list; diff --git a/job.c b/job.c index db53163..5a0ccc7 100644 --- a/job.c +++ b/job.c @@ -397,6 +397,11 @@ static void job_event_ready(Job *job) notifier_list_notify(&job->on_ready, job); } +static void job_event_idle(Job *job) +{ + notifier_list_notify(&job->on_idle, job); +} + void job_enter_cond(Job *job, bool(*fn)(Job *job)) { if (!job_started(job)) { @@ -442,6 +447,7 @@ static void coroutine_fn job_do_yield(Job *job, uint64_t ns) timer_mod(&job->sleep_timer, ns); } job->busy = false; + job_event_idle(job); job_unlock(); qemu_coroutine_yield(); @@ -860,6 +866,7 @@ static void coroutine_fn job_co_entry(void *opaque) assert(job && job->driver && job->driver->run); job_pause_point(job); job->ret = job->driver->run(job, &job->err); + job_event_idle(job); job->deferred_to_main_loop = true; aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job); } -- 1.8.3.1